Internal Thread Calculator

Formula

The formula to calculate the Minor Diameter of the Internal Thread (d) is:

\[ \text{d} = \text{D} - (1.08253 \times \text{P}) \]

Where:

\(\text{d}\) is the minor diameter of the internal thread (mm)
\(\text{D}\) is the major diameter of the internal thread (mm)
\(\text{P}\) is the pitch of the thread (mm)

Internal Thread Definition

An internal thread refers to a helical or spiral structure inside a hole, typically in materials like metal, wood, or plastic. This structure is designed to align and engage with an external thread, such as a screw or bolt, to hold pieces together. The creation of internal threads involves processes such as tapping or thread milling. The size and shape of the internal thread must match the external thread for proper function.

Example Calculation

Let's assume the following values:

Major diameter of the internal thread (D) = 20 mm
Pitch of the thread (P) = 1.5 mm

Using the formula:

\[ \text{d} = 20 - (1.08253 \times 1.5) = 18.38 \text{ mm} \]

The Minor Diameter of the Internal Thread (d) is 18.38 mm.